System and method of modes for data transmission

ABSTRACT

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus obtain a signal from a remote wireless node. The apparatus may switch between a first mode and a second mode in response to the signal. The apparatus may sense the shared transmission medium and sense if an absence of traffic is detected. The apparatus may delay data transmission for a fixed time interval from detecting the absence of traffic. The apparatus may initiate the data transmission at the end of the fixed time interval if operating in the first mode or initiate the data transmission at the end of a random time interval following the fixed time interval if operation in the second mode.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation of U.S. Non-Provisional applicationSer. No. 16/132,258, entitled “SYSTEM AND METHOD OF MODES FOR DATATRANSMISSION” and filed on Sep. 14, 2018, which claims priority of U.S.Provisional Application Ser. No. 62/559,478, entitled “SYNCHRONIZEDMEDIUM REUSE SEQUENCE” and filed on Sep. 15, 2017, both of which areexpressly incorporated by reference herein in its entirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to transmitting data according to different modes.

Background

Communications networks are used to exchange messages among severalinteracting spatially-separated devices. Networks may be classifiedaccording to geographic scope, which could be, for example, ametropolitan area, a local area, or a personal area. Such networks wouldbe designated respectively as a wide area network (WAN), metropolitanarea network (MAN), local area network (LAN), wireless local areanetwork (WLAN), or personal area network (PAN). Networks also differaccording to the switching/routing technique used to interconnect thevarious network nodes and devices (e.g., circuit switching vs. packetswitching), the type of physical media employed for transmission (e.g.,wired vs. wireless), and the set of communication protocols used (e.g.,Internet protocol suite, Synchronous Optical Networking (SONET),Ethernet, etc.).

Wireless communication networks are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, etc. These wireless networks may be multiple-access networkscapable of supporting multiple users by sharing the available networkresources. Examples of such multiple-access networks include CodeDivision Multiple Access (CDMA) networks, Time Division Multiple Access(TDMA) networks, Frequency Division Multiple Access (FDMA) networks,Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA)networks.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

The following disclosure describes methods, techniques, and protocolsfor synchronization transmissions (e.g., from access points) that arewithin range. Such transmission may be well synchronized (e.g., within1.5 μs when the fixed interval is a PIFS) to allow a receiver to lockinto a desired packet and to achieve a lower packet error rate (PER).

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may include a firstinterface configured to obtain a signal from a wireless node; and aprocessing system configured to: select operation in a first mode or asecond mode in the response to the signal; detect an absence of trafficon the shared medium during a fixed time interval; and initiate the datatransmission at the end of the fixed time interval if operating in thefirst mode or initiate the data transmission at the end of a random timeinterval following the fixed time interval if operating in the secondmode. In an aspect, the processing system is further configured toinitiate the data transmission in the first mode by generating aplurality of data frames separated by the fixed time interval, and theapparatus further comprising: a second interface configured to outputthe plurality of data frames for transmission. In an aspect, theprocessing system is further configured to terminate the datatransmission if a time period associated with the data transmissionexceeds a maximum time interval, the time period being after theinitiation of the data transmission. In an aspect, the processing systemis further configured to: generate a block acknowledgement request, andschedule transmission of the block acknowledgement request following themaximum time interval; and the apparatus further comprising a secondinterface configured to output the block acknowledgement request for thescheduled transmission. In an aspect, the processing system is furtherconfigured to initiate transmission of a block acknowledgement ifanother absence of traffic is detected on the shared medium following anend of the data transmission. In an aspect, the processing system isfurther configured to monitor the shared medium to determine one or moreparameters and provide the one or more parameters to a remote wirelessnode. In an aspect, the one or more parameters comprise at least one ofreceived signal strength from a wireless node in communication with theapparatus or detected interference associated with the shared medium.

In an aspect, the apparatus may include means for obtaining a signalfrom a wireless node. The apparatus may include means for selectingoperation in a first mode or a second mode in the response to thesignal. The apparatus may include means for detecting an absence oftraffic on the shared medium during a fixed time interval. The apparatusmay include means for initiating the data transmission at the end of thefixed time interval if operating in the first mode or initiate the datatransmission at the end of a random time interval following the fixedtime interval if operating in the second mode. In an aspect, the meansfor initiating the data transmission is configured to generate aplurality of data frames separated by the fixed time interval, and tooutput the plurality of data frames for transmission. In an aspect, theapparatus may include means for terminating the data transmission if atime period associated with the data transmission exceeds a maximum timeinterval, the time period being after the initiation of the datatransmission. In an aspect, the apparatus may include means forgenerating a block acknowledgement request; means for schedulingtransmission of the block acknowledgement request following the maximumtime interval; and means for outputting the block acknowledgementrequest for the scheduled transmission. In an aspect, the apparatus mayinclude means for initiating transmission of a block acknowledgement ifanother absence of traffic is detected on the shared medium following anend of the data transmission. In an aspect, the apparatus may includemeans for monitoring the shared medium to determine one or moreparameters and providing the one or more parameters to a remote wirelessnode. In an aspect, the one or more parameters comprise at least one ofreceived signal strength from a wireless node in communication with theapparatus or detected interference associated with the shared medium.

The method may include obtaining a signal from a wireless node;selecting operation in a first mode or a second mode in the response tothe signal; detecting an absence of traffic on the shared medium duringa fixed time interval; and initiating the data transmission at the endof the fixed time interval if operating in the first mode or initiatethe data transmission at the end of a random time interval following thefixed time interval if operating in the second mode. In an aspect, theinitiating the data transmission in the first mode comprises: generatinga plurality of data frames separated by the fixed time interval; andoutputting the plurality of data frames for transmission. The method mayfurther include terminating the data transmission if a time periodassociated with the data transmission exceeds a maximum time interval,the time period being after the initiation of the data transmission. Themethod may further include generating a block acknowledgement request;scheduling transmission of the block acknowledgement request followingthe maximum time interval; and outputting the block acknowledgementrequest for the scheduled transmission. The method may further includeinitiating transmission of a block acknowledgement if another absence oftraffic is detected on the shared medium following an end of the datatransmission. The method may further include monitoring the sharedmedium to determine one or more parameters and providing the one or moreparameters to a remote wireless node. In an aspect, the one or moreparameters comprise at least one of received signal strength from awireless node in communication with the apparatus or detectedinterference associated with the shared medium.

The computer-readable medium may include codes for wirelesscommunication executable to cause an apparatus to: obtain a signal froma wireless node; select operation in a first mode or a second mode inthe response to the signal; detect an absence of traffic on a sharedmedium during a fixed time interval; and initiate the data transmissionat the end of the fixed time interval if operating in the first mode orinitiate the data transmission at the end of a random time intervalfollowing the fixed time interval if operating in the second mode.

A wireless node for wireless communications on a shared transmissionmedium, may be provided. The wireless node including a receiverconfigured to receive a signal from a wireless node; and a processingsystem configured to: select operation in a first mode or a second modein the response to the signal; detect an absence of traffic on theshared medium during a fixed time interval; and initiate the datatransmission at the end of the fixed time interval if operating in thefirst mode or initiate the data transmission at the end of a random timeinterval following the fixed time interval if operating in the secondmode.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 illustrates a diagram of an example wireless communicationsnetwork, in accordance with certain aspects of the present disclosure.

FIG. 2 illustrates a block diagram of an example access point (AP) anduser terminals (UTs), in accordance with certain aspects of the presentdisclosure.

FIG. 3 illustrates an exemplary method for communication over a medium.

FIGS. 4A and 4B illustrate diagrams of an AP operating in a first modeand a second mode.

FIGS. 5A and 5B illustrate diagrams related to sequence robustness.

FIGS. 6A and 6B illustrates diagrams for acknowledging transmissions ina synchronized sequence.

FIG. 7 is a diagram illustrating an exemplary method for communicatingover a medium.

FIG. 8 shows an example functional block diagram of a wireless deviceconfigured to communicate over a medium.

FIG. 9 is a flowchart of a method for communicating over a medium.

FIG. 10 is a block diagram illustrating exemplary means.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

An Example Wireless Communication System

The techniques described herein may be used for various broadbandwireless communication systems, including communication systems that arebased on an orthogonal multiplexing scheme. Examples of suchcommunication systems include Spatial Division Multiple Access (SDMA),Time Division Multiple Access (TDMA), Orthogonal Frequency DivisionMultiple Access (OFDMA) systems, Single-Carrier Frequency DivisionMultiple Access (SC-FDMA) systems, and so forth. An SDMA system mayutilize sufficiently different directions to simultaneously transmitdata belonging to multiple user terminals. A TDMA system may allowmultiple user terminals to share the same frequency channel by dividingthe transmission signal into different time slots, each time slot beingassigned to different user terminal. An OFDMA system utilizes orthogonalfrequency division multiplexing (OFDM), which is a modulation techniquethat partitions the overall system bandwidth into multiple orthogonalsub-carriers. These sub-carriers may also be called tones, bins, etc.With OFDM, each sub-carrier may be independently modulated with data. AnSC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit onsub-carriers that are distributed across the system bandwidth, localizedFDMA (LFDMA) to transmit on a block of adjacent sub-carriers, orenhanced FDMA (EFDMA) to transmit on multiple blocks of adjacentsub-carriers. In general, modulation symbols are sent in the frequencydomain with OFDM and in the time domain with SC-FDMA.

The teachings herein may be incorporated into (e.g., implemented withinor performed by) a variety of wired or wireless apparatuses (e.g.,nodes). In some aspects, a wireless node implemented in accordance withthe teachings herein may comprise an access point or an access terminal.

An access point (“AP”) may comprise, be implemented as, or known as aNode B, a Radio Network Controller (“RNC”), an evolved Node B (eNB), aBase Station Controller (“BSC”), a Base Transceiver Station (“BTS”), aBase Station (“BS”), a Transceiver Function (“TF”), a Radio Router, aRadio Transceiver, a Basic Service Set (“BSS”), an Extended Service Set(“ES S”), a Radio Base Station (“RBS”), or some other terminology.

An access terminal (“AT”) may comprise, be implemented as, or known as asubscriber station, a subscriber unit, a mobile station (MS), a remotestation, a remote terminal, a user terminal (UT), a user agent, a userdevice, user equipment (UE), a user station, or some other terminology.In some implementations, an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, a Station (“STA”), or some other suitable processing deviceconnected to a wireless modem. Accordingly, one or more aspects taughtherein may be incorporated into a phone (e.g., a cellular phone or smartphone), a computer (e.g., a laptop), a tablet, a portable communicationdevice, a portable computing device (e.g., a personal data assistant),an entertainment device (e.g., a music or video device, or a satelliteradio), a global positioning system (GPS) device, or any other suitabledevice that is configured to communicate via a wireless or wired medium.In some aspects, the node is a wireless node. Such wireless node mayprovide, for example, connectivity for or to a network (e.g., a widearea network such as the Internet or a cellular network) via a wired orwireless communication link.

FIG. 1 illustrates a multiple-access multiple-input multiple-output(MIMO) system 100 with access points and user terminals in which aspectsof the present disclosure may be practiced. For example, one or moreuser terminals 120 may signal capabilities (e.g., to access point 110)using the techniques provided herein.

For simplicity, only one access point 110 is shown in FIG. 1. An accesspoint is generally a fixed station that communicates with the userterminals and may also be referred to as a base station or some otherterminology. A user terminal may be fixed or mobile and may also bereferred to as a mobile station, a wireless node, a wireless node, orsome other terminology. Access point 110 may communicate with one ormore user terminals 120 at any given moment on the downlink and uplink.The downlink (i.e., forward link) is the communication link from theaccess point to the user terminals, and the uplink (i.e., reverse link)is the communication link from the user terminals to the access point. Auser terminal may also communicate peer-to-peer with another userterminal. A system controller 130 couples to and provides coordinationand control for the access points.

While portions of the following disclosure will describe user terminals120 capable of communicating via Spatial Division Multiple Access(SDMA), for certain aspects, the user terminals 120 may also includesome user terminals that do not support SDMA. Thus, for such aspects, anAP 110 may be configured to communicate with both SDMA and non-SDMA userterminals. This approach may conveniently allow older versions of userterminals (“legacy” stations) to remain deployed in an enterprise,extending their useful lifetime, while allowing newer SDMA userterminals to be introduced as deemed appropriate.

The access point 110 and user terminals 120 employ multiple transmit andmultiple receive antennas for data transmission on the downlink anduplink. For downlink MIMO transmissions, N_(ap) antennas of the accesspoint 110 represent the multiple-input (MI) portion of MIMO, while a setof K user terminals represent the multiple-output (MO) portion of MIMO.Conversely, for uplink MIMO transmissions, the set of K user terminalsrepresent the MI portion, while the N_(ap) antennas of the access point110 represent the MO portion. For pure SDMA, it is desired to haveN_(ap)≥K≥1 if the data symbol streams for the K user terminals are notmultiplexed in code, frequency or time by some means. K may be greaterthan N_(ap) if the data symbol streams can be multiplexed using TDMAtechnique, different code channels with CDMA, disjoint sets of subbandswith OFDM, and so on. Each selected user terminal transmitsuser-specific data to and/or receives user-specific data from the accesspoint. In general, each selected user terminal may be equipped with oneor multiple antennas (i.e., N_(ut)≥1). The K selected user terminals canhave the same or different number of antennas.

The system 100 may be a time division duplex (TDD) system or a frequencydivision duplex (FDD) system. For a TDD system, the downlink and uplinkshare the same frequency band. For an FDD system, the downlink anduplink use different frequency bands. MIMO system 100 may also utilize asingle carrier or multiple carriers for transmission. Each user terminalmay be equipped with a single antenna (e.g., in order to keep costsdown) or multiple antennas (e.g., where the additional cost can besupported). The system 100 may also be a TDMA system if the userterminals 120 share the same frequency channel by dividingtransmission/reception into different time slots, each time slot beingassigned to different user terminal 120.

FIG. 2 illustrates a block diagram of access point 110 and two userterminals 120 m and 120 x in MIMO system 100 that may be examples of theaccess point 110 and user terminals 120 described above with referenceto FIG. 1 and capable of performing the techniques described herein. Thevarious processors shown in FIG. 2 may be configured to perform (ordirect a device to perform) various methods described herein.

The access point 110 is equipped with N_(ap) antennas 224 a through 224ap. User terminal 120 m is equipped with N_(ut,m) antennas 252 mathrough 252 mu, and user terminal 120 x is equipped with N_(ut,x)antennas 252 xa through 252 xu. The access point 110 is a transmittingentity for the downlink and a receiving entity for the uplink. Each userterminal 120 is a transmitting entity for the uplink and a receivingentity for the downlink. As used herein, a “transmitting entity” is anindependently operated apparatus or device capable of transmitting datavia a wireless channel, and a “receiving entity” is an independentlyoperated apparatus or device capable of receiving data via a wirelesschannel. In the following description, the subscript “dn” denotes thedownlink, the subscript “up” denotes the uplink. For SDMA transmissions,Nu_(up) user terminals simultaneously transmit on the uplink, whileN_(dn) user terminals are simultaneously transmitted to on the downlinkby the access point 110. N_(up) may or may not be equal to N_(dn), andN_(up) and N_(dn) may be static values or can change for each schedulinginterval. The beam-steering or some other spatial processing techniquemay be used at the access point and user terminal.

On the uplink, at each user terminal 120 selected for uplinktransmission, a transmit (TX) data processor 288 receives traffic datafrom a data source 286 and control data from a controller 280. Thecontroller 280 may be coupled with a memory 282. TX data processor 288processes (e.g., encodes, interleaves, and modulates) the traffic datafor the user terminal based on the coding and modulation schemesassociated with the rate selected for the user terminal and provides adata symbol stream. A TX spatial processor 290 performs spatialprocessing on the data symbol stream and provides N_(ut,m) transmitsymbol streams for the N_(ut,m) antennas. Each transmitter unit (TMTR)254 receives and processes (e.g., converts to analog, amplifies,filters, and frequency upconverts) a respective transmit symbol streamto generate an uplink signal. N_(ut,m) transmitter units 254 provideN_(ut,m) uplink signals for transmission from N_(ut,m) antennas 252 tothe access point.

N_(up) user terminals may be scheduled for simultaneous transmission onthe uplink.

Each of these user terminals performs spatial processing on its datasymbol stream and transmits its set of transmit symbol streams on theuplink to the access point.

At access point 110, N_(ap) antennas 224 a through 224 ap receive theuplink signals from all N_(up) user terminals transmitting on theuplink. Each antenna 224 provides a received signal to a respectivereceiver unit (RCVR) 222. Each receiver unit 222 performs processingcomplementary to that performed by transmitter unit 254 and provides areceived symbol stream. An RX spatial processor 240 performs receiverspatial processing on the N_(ap) received symbol streams from N_(ap)receiver units 222 and provides N_(up) recovered uplink data symbolstreams. The receiver spatial processing is performed in accordance withthe channel correlation matrix inversion (CCMI), minimum mean squareerror (MMSE), soft interference cancellation (SIC), or some othertechnique. Each recovered uplink data symbol stream is an estimate of adata symbol stream transmitted by a respective user terminal. An RX dataprocessor 242 processes (e.g., demodulates, deinterleaves, and decodes)each recovered uplink data symbol stream in accordance with the rateused for that stream to obtain decoded data. The decoded data for eachuser terminal may be provided to a data sink 244 for storage and/or acontroller 230 for further processing. The controller 230 may be coupledwith a memory 232.

On the downlink, at access point 110, a TX data processor 210 receivestraffic data from a data source 208 for N_(dn) user terminals scheduledfor downlink transmission, control data from a controller 230, andpossibly other data from a scheduler 234. The various types of data maybe sent on different transport channels. TX data processor 210 processes(e.g., encodes, interleaves, and modulates) the traffic data for eachuser terminal based on the rate selected for that user terminal. TX dataprocessor 210 provides N_(dn) downlink data symbol streams for theN_(dn) user terminals. A TX spatial processor 220 performs spatialprocessing (such as a precoding or beamforming, as described in thepresent disclosure) on the N_(dn) downlink data symbol streams, andprovides N_(ap) transmit symbol streams for the N_(ap) antennas. Eachtransmitter unit 222 receives and processes a respective transmit symbolstream to generate a downlink signal. N_(ap) transmitter units 222providing N_(ap) downlink signals for transmission from N_(ap) antennas224 to the user terminals.

At each user terminal 120, N_(ut,m) antennas 252 receive the N_(ap)downlink signals from access point 110. Each receiver unit 254 processesa received signal from an associated antenna 252 and provides a receivedsymbol stream. An RX spatial processor 260 performs receiver spatialprocessing on N_(ut,m) received symbol streams from N_(ut,m) receiverunits 254 and provides a recovered downlink data symbol stream for theuser terminal. The receiver spatial processing is performed inaccordance with the CCMI, MMSE or some other technique. An RX dataprocessor 270 processes (e.g., demodulates, deinterleaves and decodes)the recovered downlink data symbol stream to obtain decoded data for theuser terminal. The decoded data for each user terminal may be providedto a data sink 272 for storage and/or a controller 280 for furtherprocessing.

At each user terminal 120, a channel estimator 278 estimates thedownlink channel response and provides downlink channel estimates, whichmay include channel gain estimates, SNR estimates, noise variance and soon. Similarly, at access point 110, a channel estimator 228 estimatesthe uplink channel response and provides uplink channel estimates.Controller 280 for each user terminal typically derives the spatialfilter matrix for the user terminal based on the downlink channelresponse matrix H_(dn,m) for that user terminal. Controller 230 derivesthe spatial filter matrix for the access point based on the effectiveuplink channel response matrix H_(up,eff). Controller 280 for each userterminal may send feedback information (e.g., the downlink and/or uplinkeigenvectors, eigenvalues, SNR estimates, and so on) to the accesspoint. Controllers 230 and 280 also control the operation of variousprocessing units at access point 110 and user terminal 120,respectively.

In a Wi-Fi network, wireless devices such as APs and STAs may perform aclear channel assessment (CCA) to determine whether a transmissionchannel is busy or idle for purposes of determining whether data may betransmitted to another wireless device. A CCA has two components:carriers sense (CS) and energy detection. Carrier sense refers to anability of a wireless device (e.g., AP or STA) to detect and decodeincoming Wi-Fi preambles having information that enables the receiver toacquire a wireless signal from and synchronize with the transmitter,from other wireless devices. For example, a first AP may broadcast aWi-Fi signal preamble, and the Wi-Fi signal preamble may be detected bya second AP or a STA. Similarly, a third AP may broadcast a Wi-Fi signalpreamble, and the Wi-Fi signal preamble may be detected by the secondAP. When the second AP detects one or more of the Wi-Fi signalpreambles, the second AP may determine that the transmission channel isbusy and may not transmit data. The CCA may remain busy for the lengthof a transmission frame associated with the Wi-Fi preambles.

The second component of CCA is energy detection, which refers to theability of a wireless device to detect an energy level present on atransmission channel. The energy level may be based on differentinterference sources, Wi-Fi transmissions, a noise floor, and/or ambientenergy. Wi-Fi transmissions may include unidentifiable Wi-Fitransmissions that have been corrupted or are so weak that thetransmission can no longer be decoded. Unlike carrier sense, in whichthe exact length of time for which a transmission channel is busy may beknown, energy detection uses periodic sampling of a transmission channelto determine if the energy exists. Additionally, energy detection mayrequire at least one threshold used to determine whether the reportedenergy level is adequate to report the transmission channel as busy oridle. This energy level may be referred to as the ED level/ED thresholdlevel or the CCA sensitivity level. For example, if an ED level is abovea threshold, a wireless device may defer to other devices by refrainingfrom transmitting.

In one aspect of communicating over a medium, a device may reducetransmit power, which may lead to loss of coverage or throughput.Another possibility is to increase the CCA threshold (e.g., an energydetection level threshold), but doing so may create issues withcoexistence. As such, a need exists to enable medium coexistence withoutexcessively diminishing throughput or creating coexistence problems.

FIG. 3 illustrates an exemplary method 300 for communicating over amedium. Referring to FIG. 3, a first AP 302 and a first STA 306 may beassociated with a first BSS (BSS 1). A second AP 304 and a second STA308 may be associated with a second BSS (BSS 2). The first AP 302 may bewithin CCA range of the second AP 304. In various aspects, the first AP302 and/or the second AP 304 may monitor the shared transmission mediumto determine one or more parameters. In one aspect, the second AP 304may send, on a channel, a first transmission 312 to the second STA 308.In an aspect, the second STA 308 may measure the received signalstrength indicator (RSSI) of the first transmission 312, and provide theRSSI measurement in a first feedback message 314 to the second AP 304.

Referring to FIG. 3, the first transmission 312 from the second AP 304may cause interference to the first AP 302 associated with the firstBSS. In one configuration, upon detecting the first transmission 312(e.g., a preamble is detected or energy detection level is above athreshold), the first AP 302 may refrain from the transmitting becausethe medium is busy. In one configuration, the first AP 302 may detectinterference based on detecting the first transmission 312, such as bydetecting energy associated with the first transmission 312.

In an aspect, in a first mode, the first AP 302 may transmit a number ofdata frames in which each transmission is separated by a fixed timeinterval. In this first mode, each data frame may be transmittedconcurrently with another data frame transmitted by the second AP 304.In a second mode, one or more of the APs 302, 304 may transmit dataframes at different times. For example, the first AP 302 may transmit adata frame at the end of a random time interval following a fixed timeinterval. The second AP 304 may transmit a data frame at the end of adifferent random time interval following a fixed time interval.

In an aspect, although FIG. 3 depicts the network entity 310 as aseparate entity within a network managing a medium, the network entity310 may also be a component within the first AP 302 and/or the second AP304. The network entity 310 may communicate with the first AP 302 and/orthe second AP 304 (e.g., over communication link 318).

FIGS. 4A and 4B illustrate diagrams 400, 450 of an AP operating in afirst mode and a second mode. Referring to FIG. 4A, both the first AP302 and the second AP 304 may have data for transmission. After aninterframe space (IFS) such as a point coordination function (PCF)interframe space (PIFS) or a distributed coordination function (DCF)interframe space (DIFS), the first and second APs 302, 304 may performCCA. Based on the CCA, the second AP 304 may determine that the mediumis available and may transmit Packet B1 (e.g., the first transmission312) after performing CCA. The first AP 302 may perform CCA as well anddetect the packet transmission (Packet B1). In one configuration, thefirst AP 302 may determine that the medium or channel is busy and maynot transmit. In another configuration, based on a first channelinformation message 316 and/or a third channel information message 322,the network entity 310 may instruct the first AP 302 to operate in thefirst mode (via the first control message 326) and may instruct thesecond AP 304 to operate in the first mode (e.g., via a second controlmessage 328) to increase usage of a medium. In the first mode, first AP302 may wait for the transmission of Packet B1 to finish. After a fixedinterval (e.g., an IFS), during which the first and second APs 302, 304detect the absence of traffic (e.g., no traffic is detected after PacketB1 was transmitted), the first AP 302 may transmit Packet A1 (e.g., thesecond transmission 320) concurrently as the second AP 304 transmitspacket B2. After another fixed interval (e.g., PIFS or DIFS), the firstAP 302 may transmit Packet A2 concurrently with the second AP 304'stransmission of the Packet B3. After another fixed interval, the firstAP 302 may transmit Packet A3 concurrently with the second AP 304'stransmission of the Packet B4. And finally, the first AP 302 maytransmit Packet A4 concurrently with the second AP 304's transmission ofPacket B5. In an aspect, the APs may perform CCA during each of thefixed intervals.

In another aspect, one or more of the APs 302, 304 may follow a backoffprocedure (e.g., a standard backoff procedure may be defined in one ormore 802.11 specifications). Such a backoff procedure may use a certainan arbitration IFS (AIFS) and/or SLOT time parameters for the backoffcountdown. If the medium is idle, according to CCA, for the AIFS time,one or more of the APs 302, 304 may decrement a backoff counter by 1,and then the one or more of the APs 302, 304 may further decrement thebackoff counter by 1 for each consecutive SLOT time during which themedium keeps continuously idle. In an aspect, the AIFS may be equal to ashort IFS (SIFS)+(1 SLOT)=PIFS; however, the AIFS may be larger.

Once the medium is accessed, the second AP 304 may transmit a sequenceof at least one physical layer convergence procedure (PLCP) protocoldata unit (PPDU) (e.g., PPDUs B1, B2, . . . , BN). Each of the PPDUs ofthe sequence may be separated by a same AIFS time. In some aspects, theAIFS is to be equal to the PIFS (e.g., based on certain conditions).

The first AP 302 may detect at least one of the PPDUs (e.g., B1), andthe first AP 302 may halt backoff by the first AP 302, thereby deferringtransmission by the first AP 302. Once the at least one PPDU (e.g., B1)ends, the first AP 302 may sense the medium for the AIFS time, and thefirst AP 302 may decrement the backoff counter by 1. If the backoffcounter reaches 0, the first AP 302 may transmit a packet A1 (e.g., of asequence of at least one PPDU). In some aspects, the first AP 302 maytransmit the packet A1 contemporaneously (e.g., simultaneously) with thepacket B2 of the at least one PPDU. Once the packet A1 is completed, thefirst AP 302 may perform channel sensing for the PIFS time and, if thechannel is idle, the first AP 302 may transmit a packet A2. Similarly,once B2 is completed, the second AP 304 may perform channel sensing forthe PIFS time and, if the channel is idle, the second AP 304 maytransmit a packet B3. In some aspects, the first and/or second AP 302,304 may refrain from additional SLOT time sensing, e.g., until theduration of the transmission sequence (e.g., of PPDUs) exceeds atransmit opportunity (TXOP) value.

While the first and second APs 302, 304 are in the first mode, the APsmay concurrently transmit a sequence of packets. That is, the packetstransmitted by the first AP 302 may be time synchronized with packetstransmitted by the second AP 304. In an aspect, the packets may be ofthe same length and may be of relatively short lengths. In anotheraspect, the packets from the first AP 302 and the second AP 304 may beof different lengths but less than a threshold length. In anotheraspect, the packet length may be signaled by the network entity 310. Asshown in FIG. 4A, the start of the packet transmissions, regardless ofpacket length, may be at approximately the same time. In another aspect,before transmitting the sequence of packets, each of the APs may firsttransmit a clear-to-send (CTS) packet indicating that each AP intends toutilize the shared medium for data transmission. The CTS packet mayinclude a special address or indication that indicates other APs not todefer. In another aspect, each of the APs may conclude the sequence ofpackets with a CTS until the end of the maximum time interval.

As such, in the first mode, the APs may transmit a sequence ofrelatively short data frames all separated by an IFS (e.g., a PIFS). Inan aspect, the IFS or the fixed interval may be specified by the networkentity 310 and communicated to the first and second APs 302, 304. Thefirst AP 302, which was deferring initially in the second mode, afterentering the first mode, will wait until the end of the packet (e.g.,Packet B1) and then collide on all of the following frames. As noted,even if the packet sizes are not the same length, synchronization may bepreserved because one AP may wait for the other AP. In the sequence ofpacket transmissions in the first mode, the contention window for eachAP may be set to 0 or some other common value between the APs. Forexample, the fixed time interval may be a DIFS or PIFS and the APs maytransmit following a contention window in which the value is set to 0.In another aspect, instead of DIFS or PIFS, the APs may delaytransmission for a SIFS.

In an aspect, the first and second APs 302, 304 may remain in the firstmode and transmit a number of relatively short packets (or data frames)for a maximum time interval (e.g., 200 ms). Subsequently, after themaximum time interval, the first and second APs 302, 304 may terminatethe transmission. In an aspect, the first and second APs 302, 304 mayautonomously revert to the second mode without having received furthersignaling from the network entity 310. In another aspect, the first andthe second APs 302, 304 may remain in the first mode until otherwiseinstructed by the network entity 310.

FIG. 4B illustrates the diagram 450 in which the first and second APs302, 304 are operating in the second mode. In this mode, the first andsecond APs 302, 304 do not transmit over one another. In this mode,after an IFS after a transmission, both APs may perform CCA. The secondAP 304 may perform CCA and determine that the medium is available andtransmit Packet B1. The first AP 302 may perform CCA and detect PacketB1 and determine that the medium is busy. After Packet B1 is transmittedand after an IFS, the first AP 302 may wait for a random backoff time(shown as Random Backoff1 in FIG. 4B) and perform CCA again. If themedium is available, then the first AP 302 may transmit Packet A1.Subsequently, after an IFS after Packet A1 is transmitted, the second AP304 may wait a random backoff time (shown as Random Backoff2 in FIG. 4B)and then perform CCA. If the medium is available, then the second AP 304may transmit Packet B2. Unlike in FIG. 4A, the transmission times of thefirst and second APs 302, 304 are not aligned and each AP will deferwhen the other AP is transmitting.

FIGS. 5A and 5B illustrate diagrams 500, 550 related to sequencerobustness. Even assuming fine time synchronization, one AP, e.g., thefirst AP 302, may start its schedule transmission sequence with a delay.In a first option, as shown in FIG. 5A, each of the APs may wait an IFS(e.g., DIFS) and perform CCA. The first AP 302, however, may start itstransmission sequence with a delay. The network entity 310 may instructthe first AP 302 to stop transmitting if a transmission would exceed amaximum time interval. For example, the first AP 302 may stoptransmitting after Packet A3 and not transmit Packet A4. The secondoption may be preferred and may also be beneficial for a blockacknowledgment procedure.

FIGS. 6A and 6B illustrates diagrams 600, 650 for acknowledgingtransmissions in a synchronized sequence. For example, referring to FIG.6A, assuming the second option is utilized, the first and second APs302, 304 may schedule block acknowledgment requests (BARs) and blockacknowledgments (BAs). In an aspect, the BAR may be scheduled followinga maximum time interval. In another aspect, the APs may initiatetransmission of a BAR when absence of traffic is detected following thedata transmission. In an aspect, the BAR and the BA may be hardscheduled. That is, the BAR and the BA may be transmitted after themedium is seen as idle for more than PIFS.

Referring to FIG. 6B, if the late AP (or the first AP 302) is allowed totransmit, then BARs and BA could not be hard scheduled. In this aspect,the APs may use a deterministic backoff with AIFS. The deterministicbackoff may have a large AIFS to give the late AP time to finishtransmitting the late packet. In an aspect, the sequence in FIG. 6B maybe implemented using a cascade, even if the APs are within range of atransmission.

In an aspect, for FIGS. 6A and 6B, the network entity 310 may signal thefirst and the second APs 302, 304 to set an acknowledgment policy to BARfor all frames. As such, frames may not be acknowledged unless a BAR isincluded with the frame or separately transmitted after the frame, forexample. In another aspect, the APs may transmit a BAR to the STAsduring an assigned slot time.

FIG. 7 is a diagram 700 illustrating an exemplary method forcommunicating over a medium. Referring to FIG. 7, in an aspect,communication may occur over a medium when APs are loosely synchronizedand are within CCA range. In FIG. 7, APs may be instructed todeterministically collide by using IFS (e.g., PIFS) bursting. Referringto FIG. 7, a downlink controlled access interval may include a datainterval for data transmission and a BA interval for BAR and BAtransmission. During the data interval, and after an IFS, an AP maytransmit a CTS frame. An IFS after the CTS frame is transmitted, the APmay transmit a sequence of packets to its associated STAs. Each packetin the sequence of packets may be separated by a fixed time interval(e.g., PIFS). In another aspect, as shown in the previous FIGs., the APmay transmit the entire packet sequence during the data interval beforea BAR or BA is transmitted during the BA interval. After transmittingthe packet sequence, the AP may transmit another CTS frame.

FIG. 8 shows an example functional block diagram of a wireless device802 configured to communicate over a medium. The wireless device 802 isan example of a device that may be configured to implement the variousmethods described herein. For example, the wireless device 802 may bethe AP 110 and/or the UT 120.

The wireless device 802 may include a processor 804 which controlsoperation of the wireless device 802. The processor 804 may also bereferred to as a central processing unit (CPU). Memory 806, which mayinclude both read-only memory (ROM) and random access memory (RAM), mayprovide instructions and data to the processor 804. A portion of thememory 806 may also include non-volatile random access memory (NVRAM).The processor 804 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 806. Theinstructions in the memory 806 may be executable (by the processor 804,for example) to implement the methods described herein.

The wireless device 802 may also include a housing 808, and the wirelessdevice 802 may include a transmitter 810 and a receiver 812 to allowtransmission and reception of data between the wireless device 802 and aremote device. The transmitter 810 and receiver 812 may be combined intoa transceiver 814. A single transmit antenna or a plurality of transmitantennas 816 may be attached to the housing 808 and electrically coupledto the transceiver 814. The wireless device 802 may also includemultiple transmitters, multiple receivers, and multiple transceivers.

The wireless device 802 may also include a signal detector 818 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 814 or the receiver 812. The signal detector818 may detect such signals as total energy, energy per subcarrier persymbol, power spectral density and other signals. The wireless device802 may also include a digital signal processor (DSP) 820 for use inprocessing signals. The DSP 820 may be configured to generate a packetfor transmission. In some aspects, the packet may comprise a PPDU.

The various components of the wireless device 802 may be coupledtogether by a bus system 822, which may include a power bus, a controlsignal bus, and a status signal bus in addition to a data bus. Thewireless device 802 may include a medium component 824. The mediumcomponent 824, which may include one or more interfaces such as a businterface (e.g., of a processor), may be configured to perform variousoperations. The medium component 824 may be configured to a firstinterface configured to obtain a signal from a wireless node. The mediumcomponent 824 may be configured to: select operation in a first mode ora second mode in the response to the signal; detect an absence oftraffic on the shared medium during a fixed time interval; and initiatethe data transmission at the end of the fixed time interval if operatingin the first mode or initiate the data transmission at the end of arandom time interval following the fixed time interval if operating inthe second mode. The medium component 824 may be further configured toinitiate the data transmission in the first mode by generating aplurality of data frames separated by the fixed time interval, andfurther configured to output the plurality of data frames fortransmission. The medium component 824 may be further configuredterminate the data transmission if a time period associated with thedata transmission exceeds a maximum time interval, the time period beingafter the initiation of the data transmission. The medium component 824may be further configured to generate a block acknowledgement request,and schedule transmission of the block acknowledgement request followingthe maximum time interval, and output the block acknowledgement requestfor the scheduled transmission. The medium component 824 may be furtherconfigured to initiate transmission of a block acknowledgement ifanother absence of traffic is detected on the shared medium following anend of the data transmission. The medium component 824 may be furtherconfigured to monitor the shared medium to determine one or moreparameters and provide the one or more parameters to a remote wirelessnode. In an aspect, the one or more parameters comprise at least one ofreceived signal strength from a wireless node in communication with theapparatus or detected interference associated with the shared medium.

FIG. 9 is a flowchart 900 of a method for communicating over a medium.The first method may be performed using an apparatus (e.g., the AP 110,the UT 120, the wireless device 802, or the medium component 824, forexample). Although the method is described below with respect to theelements of wireless device 802 of FIG. 8, other components may be usedto implement one or more of the steps described herein.

At operation 902, the apparatus may be configured to monitor the sharedtransmission medium to determine one or more parameters and provide theone or more parameters to a remote apparatus. The apparatus may monitorthe shared transmission the shared transmission medium by determining ifsignals are transmitted on the shared transmission medium and byreceiving signals on the shared transmission medium. The apparatus maydetermine the one or more parameters by measuring the RSSI of thereceived signals or by measuring an energy detection level on thetransmission medium (e.g., interference) and by storing themeasurements. In another aspect, the apparatus may determine the one ormore parameters by receiving one or more parameters, such as byreceiving an RSSI from another wireless node (e.g., STA). For example,the first AP 302 and/or the second AP 304 may monitor the sharedtransmission medium to determine one or more parameters, and the firstAP 302 and/or the second AP 304 may provide the determine one or moreparameters to the network entity 310.

At operation 904, the apparatus may obtain a signal from a remotewireless node. For example, the signal may include an instructionconfigured to cause the apparatus to select between differenttransmission modes. In an aspect, the remote wireless node may be anetwork server. In the context of FIG. 3, the first AP 302 may receivethe control message 326 from the network entity 310, and/or the secondAP 304 may receive the control message 328 from the network entity 310.

At 906, the apparatus may select operation in a first mode or a secondmode in response to the signal. For example, the apparatus may switchbetween a first mode by setting a mode status indicator to a first valueor a second value corresponding to the selected mode. For example, thefirst AP 302 may select operation in the first mode or the second modein response to the control message 326, and/or the second AP 304 mayselect operation in the first mode or the second mode in response to thecontrol message 328.

At operation 908, the apparatus may detect an absence of traffic on theshared transmission medium during a fixed time interval. For example,the apparatus may sense the shared transmission medium by determining ifany signals are present in the medium (e.g., signals above a signalstrength) and, if not, whether the signals are absent or below a signalstrength for greater than a time duration. For example, the first AP 302and/or the second AP 304 may detect an absence of traffic on the sharedtransmission medium.

At operation 910, the apparatus may initiate the data transmission atthe end of the fixed time interval if operating in the first mode orinitiate the data transmission at the end of a random time intervalfollowing the fixed time interval if operating in the second mode. Forexample, the apparatus may begin a timer having a duration of the fixedtime interval. Upon expiration of the timer, the apparatus may initiatea data transmission if operating in the first mode. If operating in thesecond mode, the apparatus may additionally wait for a randomly selectedtime interval to elapse and then initiate the data transmission. Forexample, the first AP 302 and/or the second AP 304 may initiate a datatransmission at the end of a fixed time interval if operating in thefirst mode. In the first mode, one or more data frames transmitted bythe first AP 302 may be synchronized (e.g., concurrent) with one or moredata frames transmitted by the second AP 304. In the second mode, thefirst AP 302 or the second AP 304 may initiate a data transmission atthe end of a random time interval following the fixed time interval.

In an aspect, the apparatus may perform operation 912 and/or operation914 in order to initiate the data transmission at the end of the fixedtime interval if operating in the first mode or initiate the datatransmission at the end of a random time interval following the fixedtime interval if operating in the second mode. At operation 912, theapparatus may generate a plurality of data frames separated by a fixedtime interval. For example, the first AP 302 may generate one or more ofPacket A1 through A4, and/or the second AP 304 may generate one or moreof Packet B2-B5.

At operation 914, the apparatus may output the plurality of data framesfor transmission. For example, the first AP 302 may output the one ormore of Packet A1 through A4, and/or the second AP 304 may output theone or more of Packet B2-B5.

At operation 916, the apparatus may terminate the data transmission iftime period associated with the data transmission exceeds a maximum timeinterval. For example, the first AP 302 may terminate the datatransmission if time period associated with the data transmissionexceeds a maximum time interval, and/or the second AP 304 may terminatethe data transmission if time period associated with the datatransmission exceeds a maximum time interval.

At operation 918, the apparatus may generate a block acknowledgementrequest. For example, the first AP 302 may generate a blockacknowledgement request, and/or the second AP 304 may generate a blockacknowledgement request.

At operation 920, the apparatus may schedule transmission of a blockacknowledgment request following the maximum time interval. For example,the apparatus may detect the shared transmission medium as idle, and theapparatus may hard schedule the block acknowledgement request followingthe maximum time interval. For example, the first AP 302 may schedulethe block acknowledgement request following the maximum time interval,and/or the second AP 304 may schedule the block acknowledgement requestfollowing the maximum time interval.

At operation 922, the apparatus may output the block acknowledgementrequest for the scheduled transmission. For example, the apparatus mayinitiate, according to the scheduled transmission, transmission of theblock acknowledgment when an absence of traffic is detected followingthe data transmission. For example, the first AP 302 may output theblock acknowledgement request for the scheduled transmission, and/or thesecond AP 304 may output the block acknowledgement request for thescheduled transmission.

At operation 924, the apparatus may initiate transmission of a blockacknowledgement if another absence of traffic is detected on the sharedmedium following an end of the data transmission. For example, theapparatus may detect another absence of traffic on the shared medium,and may initiate transmission of the block acknowledgement based on thedetection of the other absence of traffic. For example, the first AP 302and/or the second AP 304 may initiate transmission of a blockacknowledgement if another absence of traffic is detected on the sharedmedium following an end of the data transmission.

FIG. 10 illustrates exemplary means 1000 capable of performing theoperations set forth in FIG. 9. The exemplary means may include meansfor monitoring the shared transmission medium to determine one or moreparameters and providing the one or more parameters to a remoteapparatus 1002. Means 1002 may include a bus interface (e.g., of aprocessor), antennas 224, antennas 252, receiver units 222, receiverunits 254, RX spatial processor 240, RX spatial processors 260, RX dataprocessor 242, RX data processors 270, transmitter units 222,transmitter units 254, TX spatial processor 220, TX spatial processors290, TX data processor 210, TX data processors 288 controller 230,controllers 280, antennas 816, transmitter 810, receiver 812, digitalsignal processor 820, and/or processor 804 shown in FIG. 2 and FIG. 8.

The exemplary means may include means for obtaining a signal from aremote wireless node 1004. Means 1004 may include a bus interface (e.g.,of a processor), antennas 224, antennas 252, receiver units 222,receiver units 254, RX spatial processor 240, RX spatial processors 260,RX data processor 242, RX data processors 270, controller 230,controllers 280, antennas 816, receiver 812, digital signal processor820, and/or processor 804 shown in FIG. 2 and FIG. 8.

The exemplary means may include means for selecting operation in a firstmode or a second mode in the response to the signal 1006. Means 1006 mayinclude controller 230, controllers 280, digital signal processor 820,and/or processor 804 shown in FIG. 2 and FIG. 8.

The exemplary means may include means for detecting an absence oftraffic on the shared medium during a fixed time interval 1008. Means1008 may include a bus interface (e.g., of a processor), antennas 224,antennas 252, receiver units 222, receiver units 254, RX spatialprocessor 240, RX spatial processors 260, RX data processor 242, RX dataprocessors 270, controller 230, controllers 280, antennas 816, receiver812, digital signal processor 820, and/or processor 804 shown in FIG. 2and FIG. 8.

The exemplary means may include means for initiating the datatransmission at the end of the fixed time interval if operating in thefirst mode or initiating the data transmission at the end of a randomtime interval following the fixed time interval if operating in thesecond mode 1010. In an aspect, means 1010 may be configured to generatea plurality of data frames separated by a fixed time interval. In anaspect, means 1010 may be configured to output the plurality of dataframes for transmission. Means 1010 may include a bus interface (e.g.,of a processor), antennas 224, antennas 252, transmitter units 222,transmitter units 254, TX spatial processor 220, TX spatial processors290, TX data processor 210, TX data processors 288, controller 230,controllers 280, antennas 816, transmitter 810, digital signal processor820, and/or processor 804 shown in FIG. 2 and FIG. 8.

The exemplary means may include means for terminating the datatransmission if time period associated with the data transmissionexceeds a maximum time interval 1012. Means 1012 may include acontroller 230, controllers 280, digital signal processor 820, and/orprocessor 804 shown in FIG. 2 and FIG. 8.

The exemplary means may include means for means for generating a blockacknowledgement request 1014. Means 1014 may include controller 230,controllers 280, digital signal processor 820, and/or processor 804shown in FIG. 2 and FIG. 8.

The exemplary means may include means for scheduling transmission of theblock acknowledgement request following the maximum time interval 1016.Means 1016 may include controller 230, controllers 280, digital signalprocessor 820, and/or processor 804 shown in FIG. 2 and FIG. 8.

The exemplary means may include means for outputting the blockacknowledgement request for the scheduled transmission 1018. Means 1018may include a bus interface (e.g., of a processor), antennas 224,antennas 252, transmitter units 222, transmitter units 254, TX spatialprocessor 220, TX spatial processors 290, TX data processor 210, TX dataprocessors 288, controller 230, controllers 280, antennas 816,transmitter 810, digital signal processor 820, and/or processor 804shown in FIG. 2 and FIG. 8.

The exemplary means may include means for initiating transmission of ablock acknowledgement if another absence of traffic is detected on theshared medium following an end of the data transmission 1020. Means 1020may include a bus interface (e.g., of a processor), antennas 224,antennas 252, transmitter units 222, transmitter units 254, TX spatialprocessor 220, TX spatial processors 290, TX data processor 210, TX dataprocessors 288, controller 230, controllers 280, antennas 816,transmitter 810, digital signal processor 820, and/or processor 804shown in FIG. 2 and FIG. 8.

In the exemplary means 1000, one or more means may be at least partiallythe same means. For example, means 1004 may include a first interfacefor obtaining the signal and means 1010 may include a second interfacefor outputting the plurality of data frames. Potentially, the firstinterface and the second interface may be the same interface.

The various operations of methods described above may be performed byany suitable means capable of performing the operations. The means mayinclude various hardware and/or software component(s) and/or module(s),including, but not limited to a circuit, an application specificintegrated circuit (ASIC), or processor. Generally, any operationsillustrated in the Figures may be performed by corresponding functionalmeans capable of performing the operations.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

As used herein, the term receiver may refer to an RF receiver (e.g., ofan RF front end) or an interface (e.g., of a processor) for receivingstructures processed by an RF front end (e.g., via a bus). Similarly,the term transmitter may refer to an RF transmitter of an RF front endor an interface (e.g., of a processor) for outputting structures to anRF front end for transmission (e.g., via a bus).

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, and also a-a, b-b, and c-c.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thepresent disclosure may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in any form of storage medium that is knownin the art. Some examples of storage media that may be used includerandom access memory (RAM), read only memory (ROM), flash memory, EPROMmemory, EEPROM memory, registers, a hard disk, a removable disk, aCD-ROM and so forth. A software module may comprise a singleinstruction, or many instructions, and may be distributed over severaldifferent code segments, among different programs, and across multiplestorage media. A storage medium may be coupled to a processor such thatthe processor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware, or any combination thereof. If implemented in hardware, anexample hardware configuration may comprise a processing system in awireless node. The processing system may be implemented with a busarchitecture. The bus may include any number of interconnecting busesand bridges depending on the specific application of the processingsystem and the overall design constraints. The bus may link togethervarious circuits including a processor, machine-readable media, and abus interface. The bus interface may be used to connect a networkadapter, among other things, to the processing system via the bus. Thenetwork adapter may be used to implement the signal processing functionsof the PHY layer. In the case of a user terminal 120 (see FIG. 1), auser interface (e.g., keypad, display, mouse, joystick, etc.) may alsobe connected to the bus. The bus may also link various other circuitssuch as timing sources, peripherals, voltage regulators, powermanagement circuits, and the like, which are well known in the art, andtherefore, will not be described any further.

The processor may be responsible for managing the bus and generalprocessing, including the execution of software stored on themachine-readable media. The processor may be implemented with one ormore general-purpose and/or special-purpose processors. Examples includemicroprocessors, microcontrollers, DSP processors, and other circuitrythat can execute software. Software shall be construed broadly to meaninstructions, data, or any combination thereof, whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise. Machine-readable media may include, by way ofexample, RAM (Random Access Memory), flash memory, ROM (Read OnlyMemory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product. The computer-program product may comprisepackaging materials.

In a hardware implementation, the machine-readable media may be part ofthe processing system separate from the processor. However, as thoseskilled in the art will readily appreciate, the machine-readable media,or any portion thereof, may be external to the processing system. By wayof example, the machine-readable media may include a transmission line,a carrier wave modulated by data, and/or a computer product separatefrom the wireless node, all which may be accessed by the processorthrough the bus interface. Alternatively, or in addition, themachine-readable media, or any portion thereof, may be integrated intothe processor, such as the case may be with cache and/or generalregister files.

The processing system may be configured as a general-purpose processingsystem with one or more microprocessors providing the processorfunctionality and external memory providing at least a portion of themachine-readable media, all linked together with other supportingcircuitry through an external bus architecture. Alternatively, theprocessing system may be implemented with an ASIC (Application SpecificIntegrated Circuit) with the processor, the bus interface, the userinterface in the case of an access terminal), supporting circuitry, andat least a portion of the machine-readable media integrated into asingle chip, or with one or more FPGAs (Field Programmable Gate Arrays),PLDs (Programmable Logic Devices), controllers, state machines, gatedlogic, discrete hardware components, or any other suitable circuitry, orany combination of circuits that can perform the various functionalitydescribed throughout this disclosure. Those skilled in the art willrecognize how best to implement the described functionality for theprocessing system depending on the particular application and theoverall design constraints imposed on the overall system.

The machine-readable media may comprise a number of software modules.The software modules include instructions that, when executed by theprocessor, cause the processing system to perform various functions. Thesoftware modules may include a transmission module and a receivingmodule. Each software module may reside in a single storage device or bedistributed across multiple storage devices. By way of example, asoftware module may be loaded into RAM from a hard drive when atriggering event occurs. During execution of the software module, theprocessor may load some of the instructions into cache to increaseaccess speed. One or more cache lines may then be loaded into a generalregister file for execution by the processor. When referring to thefunctionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer-readable medium.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared (IR),radio, and microwave, then the coaxial cable, fiber optic cable, twistedpair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Bluray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer- readable media (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

What is claimed is: 1-23. (canceled)
 24. A method of wirelesscommunications by a first apparatus, comprising: receiving a firstmessage associated with synchronized transmission on a wireless channel;determining a schedule for the synchronized transmission with at leastone second apparatus on the wireless channel based on the first message;and initiating transmission of a first sequence of packets based on theschedule, wherein a first start time of the first sequence of packetsand a second start time of at least one second sequence of packetstransmitted by the at least one second apparatus are synchronized on thewireless channel.
 25. The method of claim 1, wherein a first length ofat least one of the first sequence of packets differs from a secondlength of at least one of the at least one second sequence of packets.26. The method of claim 25, wherein each of the first and second lengthsis less than a packet length threshold.
 27. The method of claim 1,wherein a first end time of at least one of the first sequence ofpackets is unsynchronized on the wireless channel with a second end timeof at least one of the at least one second sequence of packets.
 28. Themethod of claim 1, further comprising: detecting an absence of trafficon the wireless channel, wherein the transmission of the first sequenceof packets is initiated further based on the absence of traffic.
 29. Themethod of claim 28, further comprising: performing a clear channelassessment (CCA) procedure on the wireless channel, wherein the absenceof traffic on the wireless channel is detected based on the CCAprocedure.
 30. The method of claim 28, wherein the absence of traffic onthe wireless channel is detected during an interframe space (IFS)period.
 31. The method of claim 1, further comprising: determining thewireless channel is busy; and deferring the transmission of the firstsequence of packets based on the wireless channel being busy, whereinthe transmission of the first sequence of packets is initiated afterdeferring the transmission of the first sequence of packets.
 32. Themethod of claim 31, further comprising: detecting energy on the wirelesschannel; and comparing the energy to a threshold, wherein the wirelesschannel is determined to be busy based on the energy compared to thethreshold.
 33. A first apparatus, comprising: means for receiving afirst message associated with synchronized transmission on a wirelesschannel; means for determining a schedule for the synchronizedtransmission with at least one second apparatus on the wireless channelbased on the first message; and means for initiating transmission of afirst sequence of packets based on the schedule, wherein a first starttime of the first sequence of packets and a second start time of atleast one second sequence of packets transmitted by the at least onesecond apparatus are synchronized on the wireless channel.
 34. The firstapparatus of claim 33, wherein a first length of at least one of thefirst sequence of packets differs from a second length of at least oneof the at least one second sequence of packets.
 35. The first apparatusof claim 34, wherein each of the first and second lengths is less than apacket length threshold.
 36. The first apparatus of claim 33, wherein afirst end time of at least one of the first sequence of packets isunsynchronized on the wireless channel with a second end time of atleast one of the at least one second sequence of packets.
 37. The firstapparatus of claim 33, further comprising: means for detecting anabsence of traffic on the wireless channel, wherein the transmission ofthe first sequence of packets is initiated further based on the absenceof traffic.
 38. The first apparatus of claim 37, further comprising:means for performing a clear channel assessment (CCA) procedure on thewireless channel, wherein the absence of traffic on the wireless channelis detected based on the CCA procedure.
 39. The first apparatus of claim37, wherein the absence of traffic on the wireless channel is detectedduring an interframe space (IFS) period.
 40. The first apparatus ofclaim 33, further comprising: means for determining the wireless channelis busy; and means for deferring the transmission of the first sequenceof packets based on the wireless channel being busy, wherein thetransmission of the first sequence of packets is initiated afterdeferring the transmission of the first sequence of packets.
 41. Thefirst apparatus of claim 40, further comprising: means for detectingenergy on the wireless channel; and means for comparing the energy to athreshold, wherein the wireless channel is determined to be busy basedon the energy compared to the threshold.
 42. A first apparatus,comprising: a memory; and at least one processor coupled to the memoryand configured to: receive a first message associated with synchronizedtransmission on a wireless channel; determine a schedule for thesynchronized transmission with at least one second apparatus on thewireless channel based on the first message; and initiate transmissionof a first sequence of packets based on the schedule, wherein a firststart time of the first sequence of packets and a second start time ofat least one second sequence of packets transmitted by the at least onesecond apparatus are synchronized on the wireless channel.
 43. The firstapparatus of claim 42, wherein a first length of at least one of thefirst sequence of packets differs from a second length of at least oneof the at least one second sequence of packets.
 44. The first apparatusof claim 43, wherein each of the first and second lengths is less than apacket length threshold.
 45. The first apparatus of claim 42, wherein afirst end time of at least one of the first sequence of packets isunsynchronized on the wireless channel with a second end time of atleast one of the at least one second sequence of packets.
 46. The firstapparatus of claim 42, wherein the at least one processor is furtherconfigured to: detect an absence of traffic on the wireless channel,wherein the transmission of the first sequence of packets is initiatedfurther based on the absence of traffic.
 47. The first apparatus ofclaim 46, wherein the at least one processor is further configured to:perform a clear channel assessment (CCA) procedure on the wirelesschannel, wherein the absence of traffic on the wireless channel isdetected based on the CCA procedure.
 48. The first apparatus of claim46, wherein the absence of traffic on the wireless channel is detectedduring an interframe space (IFS) period.
 49. The first apparatus ofclaim 42, wherein the at least one processor is further configured to:determine the wireless channel is busy; and defer the transmission ofthe first sequence of packets based on the wireless channel being busy,wherein the transmission of the first sequence of packets is initiatedafter deferring the transmission of the first sequence of packets. 50.The first apparatus of claim 49, wherein the at least one processor isfurther configured to: detect energy on the wireless channel; andcompare the energy to a threshold, wherein the wireless channel isdetermined to be busy based on the energy compared to the threshold. 51.A computer-readable medium storing computer-executable code for wirelesscommunication by a first apparatus, the code when executed by aprocessor cause the processor to: receive a first message associatedwith synchronized transmission on a wireless channel; determine aschedule for the synchronized transmission with at least one secondapparatus on the wireless channel based on the first message; andinitiate transmission of a first sequence of packets based on theschedule, wherein a first start time of the first sequence of packetsand a second start time of at least one second sequence of packetstransmitted by the at least one second apparatus are synchronized on thewireless channel.
 52. The computer-readable medium of claim 51, whereina first length of at least one of the first sequence of packets differsfrom a second length of at least one of the at least one second sequenceof packets.
 53. The computer-readable medium of claim 51, wherein afirst end time of at least one of the first sequence of packets isunsynchronized on the wireless channel with a second end time of atleast one of the at least one second sequence of packets.